Hundreds of people running through the streets of London, dressed in gorilla suits, may sound like monkeying around, but it’s actually pretty serious.

While the annual Great Gorilla Run is a pretty fun event, the reason behind the event is very serious. The number of Mountain gorillas around the world is declining rapidly, and if something radical isn’t done soon, our children will probably know them as an extinct species. Through the Great Gorilla Run, the Great Gorilla Organization is trying to raise money for saving the endangered primates.

The seventh edition of the Great Gorilla Run saw 700 fake gorillas (about as many Mountain Gorillas are in the wild today) line up at the starting line, for a 7 kilometer run through London. The wacky race started in central London, in front of the Minister Court, went on along the Thames to St. Paul’s Cathedral, past Tower Bridge, and all the way to the Tate Modern Art Gallery.

Participants were dressed in various gorilla outfits, from Scottish gorillas, to businessmen gorillas and even a gorilla impersonating Che Guevara.